The rectification column with the internal heat exchange is known (Japanese patent—JP 2001046803 A). According to this technical solution shown in Fig. A, internal 4′ and external 5′ spaces of one or plenty of tubes 25′ are separated from each other by upper 3a′ and lower 3b′ tube plates inside a cylindrical body 1′ of a rectification tower. The temperature difference inside and outside tubes 25′ is established by the differing pressure in these spaces 4′ and 5′. High pressure is maintained inside of tubes 25′ while a low pressure is maintained outside of tubes 25′. During a heat transfer from a high pressure side to a low pressure side through walls of tubes 25′, the one or many tubes are used as inner and outer heat exchange surfaces. The high pressure side functions as a concentration or rectifying section and the low pressure side functions as a heat extraction surface (a steaming section). Stripping vapor enters the out-side 5′ at the bottom at 10′ and leaves the out-side 5′ at the top at 7′. Stripping liquid enters the out-side 5′ at the top at 6′ and leaves the out-side 5′ at the bottom at 11′. Vapor of multi-component mixture enters the in-side 4′ of tubes 25′ below the bottom at 12′ and leaves (as an enriched fraction) the in-side 4′ at the top at 9′. Liquid of multi-component mixture enters the in-side 4′ at the top at 8′ and leaves the in-side 4′ at the bottom at 13′. Thus both, stripping material and multi-component mixture each are cycled as a vapor and as a liquid in counter current through the column 1′. Liquid reflux is generated by a condensation of vapor arising in a regular wire-wrapped screen filter 21′ in upper part of the internal 4′ tubular surface of the rectification tower with internal heat exchange. Thus, an external condenser is avoided. The space inside tubes 25′ is used as a rectifying part of the rectification tower (vapors are enriched by lower-boiling mixture components). The space outside tubes 25′ is used as a steaming section (the liquid is enriched by higher-boiling mixture components). The spaces (4) and (5) inside and outside of the tubes (25) are filled with regular packing.
The disadvantage of this rectifying column is low efficiency of heat-and-mass transfer. It is explained by the fact that heat exchange surfaces (walls of tubes) are used only for heat transfer while the masses transfer takes places in a regular packing. The supply of fluid in inter-tubular space doesn't supply efficient interaction of fluid with heat exchange surfaces.
The above mentioned disadvantage is partially eliminated in the compact rectification tower for mixed fluid separation that contains the rectification tower (WO 03/078014 A). The tower shown in Fig. B consists of the tower body 1″ with tube-grate 3″, 4″ between which heat and mass exchange tubes 2″ are fixed. The tower has a device for vapor phase remove at the top of the tower and a device for liquid phase remove at the bottom of the tower. At the bottom of the rectification tower there is a connection point (an inlet and outlet pipe 7″) for heat carrier supply and a connecting pipe (an inlet pipe 5″) for condensate return of a heat carrier. Internal spaces between heat-and-mass exchange tubes 2″ communicate each other by a fluid medium. On the top of the tower there is a connection pipe (an inlet and outlet pipe 5″) for heat carrier vapor phase remove and condensate return of heat carrier.
The pressure regulator is installed for supply of heat carrier return into the condenser. The heat exchange takes place in this tower when vapors interacts with liquid film flowing down on the internal and external surfaces of heat and mass exchange tubes. In the upper part of the tower between the tubes there is a distribution plate 8″ under the inlet pipe 5″ which provides a gravity flow of heat carrier along external surfaces of heat-and-mass exchange tubes 2″ in the form of film.
An irregular flow of fluid on the distribution plate 8″ may be a disadvantage of the rectification tower and as a consequence there is a some difference in reflux of external surfaces of the tubes 2″. It may result in irregular heat-and-mass exchange in a cross-section of the tower.
The closest prior art of the invention is a rectification tower with an internal heat-and-mass exchange Japanese patent 2004216338 A, shown in Fig. C). The rectification tower includes a rectifying section made in the form of a vertical tube heat exchanger with vapor supplied in the tubular space and vapor removed from the tubular space that consists of a body 1″, tubes 25′″ connected to this body 1′″ and tube plates 3a′″, 3b′″, thereby defining tubular 4′″ and annular 5′″ spaces in the body 1′″ for separation of multi-component mixtures into fractions, the upper vapors outlet 7′″ from the annular space 5′″ is located below the upper fluid inlet 6′″ in the annular space 5′″. Above the upper vapors outlet 7′″ there is a fluid distributor 30′″ that distributes fluid from the upper fluid inlet 6′″ into the annular space 5′″ and provides for fluid flowing along external sides of tubes 25′″. The distributor has shallow rims around all tubes 25′″ as well as along outer perimeter of the distributor, which provide for clearances with respect to all tubes 25′″ and to the inner surface of body 1′″ which rims in order to distribute the liquid evenly to all pipes and to the inner surface of body 1′″. A packing 4a′″ may be fixed in the tubular space. The fluid flows along external sides of tubes until it comes to a packed bed 5a′″ being mandatory for the shell side 5′″ of the pipes 25′″. The fluid is supplied from the external side of tubes to the packing. The tubular space performs the function of the rectifying section while the annular space performs the function of the steaming section. The fluid distributor must have an exact horizontal alignment in order to distribute the liquid evenly to all pipes.
The disadvantage of this prototype is a low efficiency of heat transfer. It is preconditioned by at least two reasons. In this prototype column, the tubular and annular spaces are filled in with the packing. The fluid flows along the external sides of tubes only up to the packed bed then the fluid is carried off from the external sides of tubes to the packing and thereby the heat and mass exchange in the column is made worse. When the fluid is supplied from the distributor into the one point on the upper surface of each tube, the fluid is not distributed evenly on the total perimeter of the external surface of tubes. Despite the exact horizontal position of the distributor and availability of spirals on tubes, the large portion of fluid flows down in stream along the external surfaces of tubes and doesn't provide for even reflux of all external surfaces of tubes that also worsens the heat and mass exchange.